Ovulation Help? and when should i test?

I know this might sound silly but I've never really thought about it before, can you ovulate during your af whilst you're still bleeding or is it always when you've stopped bleeding?
This is my first proper period in 2 years as I've come off the pill and I don't know my cycle length or anything. I'm still on my af at the moment though so I can roughly see how long I'll be on my af for.
The reason I'm asking is because before the pill I used to bleed constantly, really heavy for about a week and a half - 2 weeks so does that mean I'll ovulate later in my cycle or I'll ovulate whilst I'm bleeding?
Also cause I was on the pill my cycle still might be irregular or so I've heard it might take a while for my af to come again so when should i test rather than waiting for an af that might take months to come?
Thanks in advance
x